‘Hydrogen evolution’ may provide a sustainable energy supply

Published online 14 May 2014

Habib Maroon

Researchers have discovered a metal-free catalyst,
suitable for commercial application, which can play a part in splitting water
to produce hydrogen electrochemically — via a process called the hydrogen
evolution reaction (HER).

A study led by
Shizhang Qiao of the University of Adelaide and including Yihan Zhu and Yu Han
of KAUST, Thuwal, Saudi Arabia, tested a catalyst for HER consisting solely of
carbon and nitrogen.

Hydrogen is potentially
the planet’s most sustainable energy source. It has a higher energy density
than other fuels, does not emit pollutants when burnt, and, as a component of
water, is plentiful.

HER typically
requires efficient catalysts and platinum has historically provided the best
results, but is scarce and expensive. Other transition metals such as nickel or
molybdenum are less efficient and susceptible to corrosion.

Hybrids of
graphitic-carbon nitride and nitrogen-doped graphene catalysed HER as
efficiently as most transition metal-based catalysts, without the
susceptibility to corrosion. The catalytic properties of the hybrid material were
a result of synergy between the two components. The carbon nitride provides
sites for hydrogen adsorption whilst the N-graphene facilitates the transfer of
electrons during the process of proton reduction.

“This study provides clear and solid evidence
that, similar to precious metals, well-designed metal-free counterparts have
great potential for highly efficient electrocatalytic HER, thus expanding the
spectrum of catalysts for HER and other energy-related electrocatalytic
reactions.” says Qiao.